The Bay State Senate air war has begun — and it's surprisingly positive.

Sen. Scott Brown, in a highly competitive race with Harvard Law School professor Elizabeth Warren (D), launched his first television ad of the cycle today. Backed by a significant six-figure ad buy on broadcast and cable TV, the positive 30-second spot highlights the Republican's independence and biography.

It's competing with an ad from Warren, backed by about $800,000, that's already on the air.

Brown's spot emphasizes his defying-the-odds story and includes a potent video clip from a "60 Minutes" piece about the Senator. "He's turned out to be unpredictably independent, and beholden to no one," CBS correspondent Lesley Stahl says.

Brown, a Republican in a state that heavily favors Democrats, makes no mention of his party affiliation in his ad. To win his first full term, he'll have to appeal to a large swath of the electorate that will be voting for President Barack Obama this November.

The new ad moves the media spotlight to Brown after almost two weeks when it has been focused, rather harshly, on Warren. The Boston Globe dubbed last week her "worst stretch" as a candidate for Senate.

Warren's campaign fumbled the revelation that the candidate considered herself a Native American and had listed herself as such in professional law school directories during an early part of her career. Warren's camp said the professor was proud of her heritage. One genealogist found Warren to be 1/32 Cherokee.

While Warren's stumble was significant, it wasn't disqualifying and the race remains, essentially, a dead heat.

Brown's spot will run in the Boston, Springfield, Providence and Albany markets, and on cable across the state. Warren's current spot, released May 2, can be seen here: